This invention concerns magnetic head and magnetic storage for magnetic disk apparatus etc., and especially, concerns the magnetic storage apparatus using magnetic head and suitable for the high frequency record.
FIG. 2(a) is a strabismus figure which shows the general recording and reproducing separation type magnetic head. Slider 7 is worn in the tip of head gimbal assembly (HGA)8. This extension strabismus figure of slider 7 is shown in FIG. 2(b). And, a typical part limits chip strabismus figure of the part (A part of FIG. 2(b)) of the recording and reproducing head are shown at FIG. 2(c). The position of air bearing surface described for the reference in each figure, because the direction of the slider was not fixed in each figure. As it is shown at. FIG. 2(c), the recording head utilizes electromagnetic induction by coil 6, and the reproducing head has magnetic sensor 4 between upper magnetic film 2 and lower magnetic film 3. At FIG. 2(c), upper magnetic film 2 and upper core 1 placed in the top, coil 6, etc. showed the condition that the right side of the figure was cut. Lead wire 5 take out the signal from magnetic sensor 4.
It is general to design the thickness of the core deeply in order to generate the more resistant magnetic field, and in order to saturate the core, for conventional record reproduction separate type magnetic head in order to ensure the overwriting performance. Upper core 1 is formed generally by plating or sputter process. From the problem on the manufacturing process, upper 1 tip minute 1a other tend to (in the following, slope 1b of upper core). Still, other part is the thickness with the same abbreviation. This is explained using FIG. 3.
FIG. 3 is sectional view of the part of recording and reproducing head. D1 thickness of tips minute 1a of upper core 1 and d2 thickness of coil 6 upper part 1c (the part which is almost parallel to the substrate and is not in slope 1b) of upper core 1 are almost same. In the FIG. 13 is the nonmagnetic material which forms the gap.
As a result of relating to the matter of the above mention, there is conventional technologies following. Laid-open No. 58-13712) discloses the technology that the upper core is thickened for the upper magnetic film (the lower core) in order to prevent the magnetic saturation in the part (the part which corresponds to slope 1b of said upper core) in which cross section of the core decreases most from the relationship between coverage factor. And, in the laid open 9-7125, the thickness of the magnetic yoke is ensured by joining the upper magnetic film to lower magnetic film in the part without a magnetic flux perception element in order to thin the thickness of the upper magnetic film (the lower core). And, in the laid open 9-169212, the stabilization of the record magnetic field is attempted by using double upper cores and adopting the material with the high saturation magnetic field. And, in the laid open 9-106509, by making the multilayer coil and shortening the magnetic path length, lowering impedance, the risetime of the record current is shortened.
Recently, it has been required that magnetic storages such as magnetic disk apparatus transfer data at high speed with miniaturization and capacity enlargement. With this, the magnetic head is required that the record and the regeneration in high frequency are possible. It is necessary that impedance of the head is become small and the risetime of the record current is shortened by decreasing the magnetic path length and reducing the winding number of the coil, etc. to realize high speed transfer for the high-speed writing necessary for the head. However, the problem that the magnetic field change was retarded for the change of the writing current became tangible as it becomes a high frequency, as it is insufficient only in the shortening in the current risetime,. This causes deterioration of the overwriting performance and nonlinear strain, and it becomes a reason why reliability and performance of apparatus remarkably lower.
FIG. 5 is the graph which shows the frequency dependence of generation magnetic field, and it has shown the relationship between magnetic field strength and record frequency of the gap position. The degradation in the high frequency is big, though the magnetic head shown in FIG. 3 generates high magnetic field as show in FIG. 5 as thick film. Reversely, the quantity of generating magnetic field decreases, as it is shown in the Figure as a thin film, when the thickness of the core is thinned in order to improve characteristics in high frequency, and the overwriting performance as a necessity is not obtained.
In the laid-open No. 58-137120, the record in the high frequency is not considered, the technology has thickened the upper core for the upper magnetic film (the lower core).
And, in the laid open 9-7125 and laid open 9-69212, the record in the high frequency is not considered, either.
In the laid open 9-106509, the delay of the magnetic field for the current does not disclose.
The first purpose of this invention is to offer the magnetic head which has excellent rapid recording performance and overwriting performance which does not deteriorate in high frequency.
The second purposes of this invention are to offer the magnetic storage apparatus which is excellent in high speed transfer, and is excellent in the overwriting performance.
In order to realize above first purpose of this invention, in the magnetic head of this invention, said magnetic head has features that the thickness of the upper part of the upper core is less than the thickness of the tip minute of the upper core, or the thickness of the tip minute of upper magnetic film is thicker than the thickness of the other part of upper magnetic film or are there both of above structure.
D1 greater than d2 and d2 would satisfy the condition over 10% of d1 when the thickness of the upper part of the upper core is d2 and the thickness of tip minute of upper is d1. In addition, it is desirable that d2 has range from 90% to 10% of d1 and it is more desirable from 80% to 20% range, and it is the most desirable from 70% to 30% range.
The thickness of the upper magnetic film is that the thickness of the part, namely the part in FIG. 2 in the lower of upper part 1c of the upper core, which faces the upper part of the upper core. This is correspondent to the part under the essential part of the abbreviation coil. The part which is connected with the upper core in the side which is reverse to the tip minute of the upper magnetic film may be thicker than it, even if the thickness is equal to the thickness of the upper magnetic film. It is central most portion of the coil, and essential part of the coil does not contain whole about {fraction (1/10)} in tip minute side (the left side in FIG. 8 which explains in practical example after) and the reverse side (the right side of the same Figure) of the coil. In short, the thickness of the part under about {fraction (1/10)} of tip minute side of the coil and the reverse side do not become the thickness of the upper magnetic film.
D3 greater than d4 condition is satisfied, when the thickness of the upper magnetic film is d4 and the thickness of the upper magnetic film of the part which faces for the tip minute of the upper core is d3, and d4 is over 10% of d3. In addition, d4 has desirable range from 90% to 10% of d3, and has more desirable range from 80% to 20%, and the most desirable range from 70% to 30%.
In the following, the action of this magnetic head is explained. The delay of the change of record magnetic field for the change of the record current occurs from skin effects and transfer of magnetic domain wall, generation of eddy current, etc. On these, the effect can be reduced by thinning the thickness of the core. FIG. 4 is the graph which shows example of bark effect, and it has shown the relationship between frequency and bark depth. The horizontal axis shows the frequency of the record current, and the vertical axis shows the distance from the core surface where the direction of the magnetization changes in proportion to the frequency. The material property of ferrite generally used as core material of recording head is used. In the region which exceeds 100 MHz, the direction of the magnetization for change of current follows in only the part under about 0.5 xcexcm. That is to say, it is shown to be the region where the magnetic field of high frequency does not come out, even if the core is thickened over 1 xcexcm.
Though degradation minute in the high frequency decreases, when the way which showed the relationship between magnetic field strength and record frequency of the gap position in advance using FIG. 5, only making the film thickness of the core to be thinned, the magnetic saturation happens in the part in which the core width narrows, and the absolute value of magnetic field strength in the gap part is not sufficiently obtained. The degradation in the high frequency increases, when the film thickness is thickened in order to prevent that. In this invention, by thinning only the part which the core does not concentrate a magnetic flux because of expanding in the track width direction, by doing the reaction for writing current which flows in the coil speedily, while the magnetic field strength of the gap part is kept, the problem of the high frequency was solved.
In order to achieve above second purpose, in the magnetic storage apparatus of this invention, A magnetic recording apparatus which comprises: a magnetic recording medium which has a recorded plane of information and rotatable; a driving means which rotates the magnetic recording medium in high speed; a slider which has a magnetic head writing information on a magnetic disk and reading information from the magnetic disk and moving in the recorded plane of said magnetic recording medium; an actuator which positions the magnetic head for the fixed position on said magnetic recording medium in the high speed; a control means for control of rotation drive of the drive means, control of the transfer of the said actuator and control of reading or writing information of said head, wherein the thickness of the tip minute of the upper magnetic film is thicker than the thickness of the other part of said upper magnetic film, and the thickness of the tip minute of the upper magnetic film is thicker than the thickness of the other part of said upper magnetic film.